The present invention relates to an AtomChip device and, in particular to an AtomChip device that extends the lifetime of cold neutral atoms, which it trapped in an atom microtrap, with, regard to existent AtomChip devices that include pure metal components, by use of metal alloys and at especially low working temperatures.
The AtomChip is a device aimed at realizing quantum technology devices in which the rules of quantum mechanics are used to realize applications such as ultra sensitive clocks, gravitation and acceleration sensors, quantum cryptography (secure communications), and quantum computing, to name a few.
A typical, conventional AtomChip is composed of a substrate upon which an electrically conductive functional layer is disposed. In the case that the substrate is not electrically insulating, a layer of electrically insulating material will be disposed between the substrate and the functional layer. The AtomChip's conducting element, through which an electrical current flows creating a magnetic field in case of DC electrical current or electromagnetic field in case of AC electrical current that will be referred to as internal fields, is within the functional layer, as a part of it, beneath it, or in any other suitable structure. The form of the AtomChip's conducting element determines the distribution of potentials of the internal fields, which affect the trapping performance. This form can be Z-shaped, U-shaped, conveyer belt shape or in a variety of other shapes or combinations of shapes. External bias fields are necessary in many cases.
The AtomChip device is located within an ultra high vacuum chamber. Commonly, the atom trapping on AtomChips is by means of only magnetic fields. In the more advanced AtomChip devices, atoms within the vacuum chamber are influenced by internal magnetic and electric fields, by light fields whose sources can be laser sources, some of which are reflected by the functional layer, if it has a mirror nature, and by electrical fields and magnetic fields generated by elements outside of the vacuum chamber, which will be referred to as external fields. The combination of these influences, if performed correctly, traps cold neutral atoms in very close proximity to the AtomChip in the atom microtrap.
The elements of the AtomChip and in particular the functional layer and the AtomChip's conducting element are substantially composed of pure metals.
Due to harmful effects such as magnetic thermal noises, as well as background noises, the time interval of the atom trapping is limited, the atoms escape the trap, and the cloud that they create fades with time. The intensity of the magnetic noise drastically increases with reduction of the distance between the trap center and the AtomChip surface [5], [6].
The typical lifetime of atoms trapped at the distance of 3 μm from an AtomChip surface in a conventional AtomChip device is about 0.5 seconds, the magnetic noise portion in the lifetime limitation being 80%, see for example [1].
Besides the lifetime limitation (losses), the magnetic noise and background noises increase the temperature of the trapped atoms (heating) and destroy their coherence (decoherence).
Reduction of the magnetic noise is needed for all applications of the AtomChip. For example, it is important for a quantum gravity gradiometer, where the AtomChip is used as an interferometer based gravity sensor. The sensitivity of this device is limited by the magnetic noise [7]. For an atomic clock the magnetic noise limits the frequency stability, which determines the atomic clock precision [8].
There is thus a widely recognized need for, and it would be highly advantageous to have an AtomChip device, whose magnetic noise level would be significantly less than that which can currently be achieved in existent AtomChip devices.